In a victory for people with cancer and other serious medical problems, the White House agreed Friday to help close a loophole in the Senate health care bill allowing annual dollar limits on their care.

"The president has made it clear that health insurance reform legislation should prevent insurance companies from placing annual limits on health expenditures that can force families into financial ruin," said White House spokesman Reid Cherlin. "We will continue to work with Congress on this policy."

"The bottom line is they are going to try to improve the Senate bill," said Stephen Finan, a policy expert with the American Cancer Society Cancer Action Network, which first called attention to the problem.

Tucked in a clause of the Senate bill captioned "No lifetime or annual limits" is a provision that would in fact permit such caps.

As currently written, the Democratic bill would allow insurance companies to place annual limits on the dollar value of medical care, as long as the limits are not "unreasonable." The legislation does not define what level of limits would be allowable, delegating that task to administration officials.

Proponents said such limits are necessary to prevent premiums from going up overall.

Finan said that White House health reform director Nancy Ann DeParle agreed in a call Friday afternoon with cancer society officials to work to change the Senate language. The idea would be to first narrow the range of limits that could be imposed, and then gradually phase them out altogether over several years. Senior Senate and House staffers also took part in the call.

"The primary purpose of insurance is to protect people against catastrophic loss," said Finan. "If you put a limit on benefits, by definition it's going to affect people who are dealing with catastrophic loss."

The 2,074-page Senate bill would carry out Obama's plan to revamp the health care system, expanding coverage to millions now uninsured and trying to slow budget-busting cost increases. A tentative deal among Democrats to back away from creating a new government program to compete with private insurers appears to have overcome a major obstacle to passage.

Under both the Senate and House health care bills, most of the expansion of health insurance coverage won't take place until three to four years after enactment. Democrats have touted a series of consumer protections as immediate benefits Americans will secure through the legislation.

In the Senate, two key committes disagreed over how to handle annual limits.